Page:Popular Science Monthly Volume 72.djvu/389



N the latter part of the seventeenth century, long prior to the discovery of oxygen, the English chemist, John Mayow, had laid hold of the important principle that there is something in the air necessary for combustion; that this something is capable of exerting its influence whether it exists free in the air or is combined in the substance undergoing combustion. Further, he pointed out that in the processes of burning and breathing there is a certain definite relationship in that both consist in the consumption of the so-called igneo-aerial particles of the air. He made clear by experiment that the views then prevailing regarding respiration, in which it was held that breathing serves to cool the heat of the heart or to facilitate the passage of the blood from the right to the left side of the heart were quite erroneous. He maintained that in breathing, something belonging to the air, something essential for sustaining life passes from the air into the blood. To quote from his own statement: "On the one hand it clearly appears that animals exhaust the air of certain vital particles which are of an elastic nature. On the other hand there can not be the slightest doubt but that some constituent of the air absolutely necessary to life enters into the blood in the act of breathing."

We fully understand to-day that Mayow's igneo-aerial particles were what we call oxygen, and that in some mysterious fashion he had